Sound-dampening structure for suction cleaners



'May'26, 1959 1 K. J. WAHLBORG ETAL 2,888,093

SOUND-DAMPENING STRUCTURE FOR SUCTION CLEANERS Filed May 17, 1955 2 Sheets-Sheet 1 WKda-Z! i 3770/?A/E) M zvvgrqks BY ZM May 26, 1959 I K. J. WAHLBORG ET AL v v SOUND-DAMPENING STRUCTURE FOR SUCTION CLEANERS Filed May 17, 1955 2 Sheets Sh eet 2 United States Patent F SOUND-DAMPENING STRUCTURE FOR SUCTION CLEANERS Karl John Wahlborg, Stockholm-Vallingby, and Lars Johan Faith-Ell, Stockholm, Sweden, assignors to Aktiebolaget Elektrolux, Stockholm, Sweden, a corporation This invention relates to suction cleaners of the household type, and is particularly concerned with dampening soundproduced during operation of cleaners of this kind.

It is an object of the invention to provide in suction cleaners of the household type improved sound-dampening structure in whichnoise produced by air flowing therethrough is silenced to a marked degree. This is accomplished by providing a sound-dampening wall member which is interposed between the air outlet of the motor-fan unit and the discharge end of the suction cleaner, such wall member having one or more channels embodied therein which serve to silence air flowing therethrough. More particularly, all of the air discharged by the fan is arranged to flow through the motor to effect cooling thereof, and thereafter flow through the aforementioned channels. A throttling effect is imparted to air during flow thereof through the motor, the air outlet thereof being of essentially the same size as that of the discharge opening of the suction cleaner. Further, the channels forming a part of the sound-dampening wall member have a well-defined change in cross-section from the inlet to the outlet ends thereof, the inlet ends being contracted with respect to the outlet ends.

Further objects and advantages of the invention will become apparent as the following description proceeds, and the features of novelty which characterize the invention will be pointed outwith particularity in the claims annexed to and forming a part of this specification.

. casing 11.

For a better understanding of the invention,.reference may be had to the following description taken in connection with the accompanying drawings, in which: .Fig. 1 is a side view of a suction cleaner embodying the invention; 1 Fig. 2 is an exploded perspective view of the suction cleaner shown in Fig. 1 to illustrate parts more clearly;

Fig. 3 is an enlarged fragmentary view, partly broken away and in section, of the suction cleaner illustrated in Figs. 1 and 2;

Fig. 4 is a view in elevation of a part of the suction cleaner shown in Figs. 2 and 3; and

Fig. 5 is a sectional view taken at line 55 of Fig. 4.

Referring to the drawings, the invention is shown in connection with a horizontal tank-type cleaner 10 having a casing 11 which is provided with a handle 12 and runners 14 which extend lengthwise of the casing and are fixed thereto in any suitable manner to facilitate movement thereof on a supporting surface. A front end cover 15, partly shown in Fig. l, is provided for the casing 11 to close an access opening of a space within which a dust bag (not shown) is adapted to be positioned. The cover 15 is formed with an opening 16 to which a flexible suction hose (not shown) is adapted to be connected.

A motor-fan unit 17 is located within the casing 11 at a. region adjacent the dust bag, such unit including a centrifugal fan 18 carried at one end of an electric motor 19. The motor-fan unit 17 is controlled by a switch 20 which is arranged to be actuated by a button 21- located at the 2,888,093 Patented May 26, 1959 ICC top of the casing 11. The motor-fan unit 17 isiesiliently mounted at 22 to a reenforcing member or flange 23 provided at the inside of the casing 11. The motorfan unit mounting 22 includes a resilient member 24 formed of a material like rubber, for example, which bridges the gap between the member 23 within the casing 11 and the motor 19 thereby sealing and closing the annular passage 25 about the fan 18 and motor ,19, so that air cannot flow freely over the exterior surfaces of motor-fan unit 17 from the front to the rear of the casing 11.

When the suction cleaner is being operated and the fan 18 driven by the motor 19, dust-laden air is drawn through the suction hose into the interior of the casing 11. During the cleaning operation, dust collectsinthe dust bag, and air free of such dust passes through the dust bag into the inlet 26 of the fan 18. The air is discharged from the fan 18 and flows through the motor :19 to eflect cooling thereof, and thereafter is discharged through an opening 27 in a rear end cover 28 which is ecc'entrically disposed with respect to-vthe. axis ofnthe In accordance with the invention, in order to dampen objectionable sounds produced during operationof the suction cleaner, an aperturedsound-dampening, wall member 30 is interposed between the motor-fan unit. 17 and the opening 27 through which air is discharged from the casing 11. The wall member 30 is provided with a flange 31 at the outer periphery thereof which is adapted to be positioned in a groove formed. by a reinforcing rib 32 fixed to the inside of the casing 11. The wall member 30 is clamped and held against the rib 32 by an end frame 33, both the wall member and end frame .being apertured at the corners to receive threaded bolts 34 adapted to be threadedly connected to the rib 32 at openings in the corners thereof, as best seen in Figs. 2 and3. The wall member 30 is formed with an opening 35'adapted to receive a threaded bolt 36 for, securing the rear end cover 28 in position, as shown in Fig. 3. I t n Referring to Figs. 2 and 3, it will be seen that-the sound-dampening wall member 30 is formed with'apair of openings at the bottom corners thereof from which hollow sleeve sections 38 extend toward the motor19, such sleeve sections being essentially parallel lto the motor shaft. About the hub and outer peripheral edge of the wall member 30 is positioned a very fine filter 39, the outer face of the wall member being concave-shaped to form a space 40 of annular form which is" defined in part by the filter 39. i

The hollow inner part of the rear end cover 28 is formed with a plurality of vertically extendingfins or baffles 41 between which a number of passages 42 are provided. When the filter 39 is positioned between the wall member 30 and rear end cover 28, as seen in Fig; 3, the filter is held in place and prevented from flexing toward the discharge opening 27 by the fins or baffles, 'the eitreme inner edges of which are in intimate contact with the outer face of the filter 39. Since the rear end cover 28 nests within the end of the casing 11-whose extremity is defined by the end frame 33 fixed thereto, the ribbing 41 and filter pad 39 in contact therewith define a plurality of passages 42 within the casingin a'plane transverse to its axis for dividing the air into a plurality-of streams and directing the several streamsthrough the passages toward the eccentrically disposed outlet 27.

It has been discovered that the wall member 30, hav ing the hollow sleeve sections 38, contributes to a great extent to dampen objectionable sounds produced when the suction cleaner is being operated. In order to ob tain the optimum benefit of the wall member 30 for this purpose, the passage 25 about the motor-fanv'unit 17 is blocked oil by the diaphragm 24 all ot the air drawn into the fan inlet 26 and discharged from the fan flows through the shell of the motor 19. Further, the inlet 43 and outlet 44 of the motor 19 are of such size that a throttling effect is imparted to air flowing therethrough, the outlet 44 being of annular form and enveloped by an apertured cage enveloping the commutator end of the motor, as best seen in Fig. 2.

It will now be understood that all of the air circulated through the casing 11 passes through the shell of the motor 19 and passes into a chamber or space 45 which is defined by a first end wall formed by the diaphragm 24 and the motor 19, and a second end wall formed by the sound-dampening wall member 30-. Further, the hollow sleeve sections 38 extend from the second end wall or wall member 30 toward the first end wall of which diaphragm 24 forms a part, the air inlet ends 46 of the hollow sleeves being positioned a greater distance from the wall member 30 than the air outlet 44 of the motor 19. Hence, air discharged from the outlet 44 into the space 45 flows in a path of flow having a reverse bend before passing into the hollow sleeves 38 at the inlets 46 therein.

From the hollow sleeves 38 the air flows into the space 40 and passes through the fine filter 39, the latter having sound-absorbing properties by virtue of its position at the extreme edges of the fins or baffies 41. The air then flows upwardly in the channels 42 at the inside of the rear cover 28 and is discharged through the Opening 27 therein, the axis of which is inclined to the horizontal and directed upwardly.

As pointed out above, a throttling efiect is imparted to air when it flows through the shell of the motor 19, the cross-sectional areas of inlet and outlet 43 and 44 desirably being of substantially the same size. Also, it has been found that, when the sound-dampening wall member 30 is employed, it is advantageous to make the discharge opening 27 in the rear end wall 28 of approximately the same size as the outlet 44 at the air discharge end of the motor shell.

The size of the channels 37 formed by the hollow sleeves 38 also plays an important part in the effectiveness of the sound-dampening wall member 30. It has been discovered that optimum results are obtained when each channel 37 has a lengthwise distance in the neighborhood of from one-half to the entire average or mean peripheral distance about the channel and desirably about three-fourths of the entire average or mean peripheral distance about the channel. Further, the diameter of the discharge opening 27 in the rear end wall 28 should be in the neighborhood of from 2% to 3 /4 times the axial distance of that opening and desirably about 3 times the axial distance of the opening.

' By Way of example and without limitation, suction cleaners like that illustrated and described herein have been constructed in which the cross-sectional areas of the air outlet 44 of the motor 19 and discharge opening 27 in the rear end cover are about 2.325 square inches for a cleaner of normal household size. Each of the channels 37 is about 3 inches long, which is approximately equivalent to three-fourths of the total average or mean peripheral distance about the channel. With the air inlet and outlet for the motor having the dimensions given above, a throttling effect is imparted to air flowing through the motor 19, as previously explained. The air discharged from the motor outlet 44 passes into the space 45 which has a cross-sectional area considerably larger than that of the outlet 44.

The air, after a reverse bend movement, enters the inlets 46 of the channels 37 which have a well-defined change in cross-section from the inlet to the outlet ends thereof; that is, the inlet ends 46 of the channels 37 are smaller in cross-section than the outlets thereof at the vicinity of the openings in the wall member 30. By virtue of the fact that the inlets 46 of the channels 37 are contracted with respect to the outlets at the regions 4 of the openings in the wall member 30, an extremely good silencing effect is obtained. After passing through the filter 39, which functions as a silencer by absorbing noise, the air is discharged-upwardly through the opening 27 in the rear wall, as previously explained.

While a particular embodiment of the invention has been shown and described, such variations and modifications are contemplated as fall within the true spirit and scope of the invention, as pointed out in the following claims.

What is claimed is:

1. In a suction cleaner having a casing provided with an inlet and outlet for air, means including a motor-fan unit in said casing for circulating air therethrough, said unit including a motor and a fan driven thereby, and means comprising an axially extending part of said casing and a wall transverse thereto to form a space into which air passes from said motor-fan unit, said space having a cross-sectional area substantially equal to that of said casing, said wall being apertured to provide one or more openings, one or more sleeve-like members which are carried by said wall and each of which communicates with one of the openings therein, each opening in said wall and the sleeve-like member communicating there with forming a hollow channel which is spaced from said casing and extends axially of the latter in a direction from said wall toward said motor-fan unit.

2. Apparatus as set forth in claim 1 in which said hollow channel or channels have a well-defined change in cross-section from the inlet to the outlet ends thereof, each channel having a lengthwise distance in the neighborhood of from one-half to the entire average or mean peripheral distance about the channel.

3. Apparatus as set forth in claim 1 in which the crosssectional area of each of said channels is smaller at the inlet than at the outlet thereof.

4. Apparatus as set forth in claim 1 which includes means to flow all of the air discharged from said fan through said motor, the last-mentioned means including structure to provide a seal between said casing and the motor-fan unit, said sealing structure defining another wall of the space into which air passes from said motorfan unit, and said motor being formed with an outlet for air having a cross-sectional area approximately the same as that of the outlet for said casing, the diameter of the outlet for said casing being in the neighborhood of from 2% to 3% times the axial distance of such outlet.

5. Apparatus as set forth in claim 1 in which said casing is of the horizontal tank type and includes an end cover having said outlet therefor, a filter disposed between said wall and said end cover, said outlet for said end cover being disposed in the upper part thereof and having its axis inclined to the horizontal and directed upwardly therefrom, and means including a plurality of vertically extending ribs at the interior of said cover, said ribs being in physical contact with one face of said filter and forming therewith elongated passageways for flowing air toward said outlet in said cover. 7

6. Apparatus as set forth in claim 1 in which said casing is of the horizontal tank type and includes an end cover having said outlet therefor, said outlet having its axis inclined to the horizontal and directed upwardly therefrom, a filter disposed between said wall and said end cover, said filter tending to be flexed toward the outlet in said end cover during operation of the cleaner, and means at the interior of said end cover which is in physical contact with the discharge face of said filter to retain the latter in position and provide an air passageway defined by the discharge face of said filter and the interior of said end cover.

7. Apparatus as set forth in claim 1 which includes means to flow all of the air discharged from said fan through said motor, the last-mentioned means including structure to provide a seal between said casing and said motor-fan unit, said wall forming a partition in said casing from which said hollow channel or channels extend toward said motor-fan unit, said motor having an outlet for air which is nearer to said partition than the region at which air enters the inlet end of each channel.

8. In a horizontal tank-type suction cleaner comprising a casing through which air is adapted to be circulated and having a rear end cover formed with an outlet eccentric with respect to the axis of said casing, a removable filter pad of sheet-like form or the like, and holding means including said end cover for removably holding said filter pad in an operating position in said casing to filter air flowing therethrough, said last-mentioned means including ribbing which is distributed about the interior of said end cover and, when said filter pad is held in its operating position in said casing by said holding means, is disposed within said casing and extends axially thereof and at its extremity physically contacts the face of said filter pad from which air emerges therefrom, and said ribbing and filter pad in contact therewith defining a multiplicity of passages within said casing in a plane transverse to its axis for dividing the air into a plurality of streams and directing the streams through said passages toward the eccentrically disposed outlet.

9. A horizontal tank-type suction cleaner comprising a casing through which air is adapted to be circulated, a rear end cover nesting within an end of said casing, said end cover having an outlet eccentric with respect to the axis of said casing, a removable filter pad of sheet-like form or the like, and holding means including said end cover for holding said filter pad in an operating position in said casing to filter air flowing therethrough, said lastmentioned means including spaced apart elongated ribs at the interior of said cover which, when said filter pad is held in its operating position in said casing by said holding means, are disposed within said casing and extend axially thereof and at their extremities physically contact the face of said filter pad from which air emerges therefrom, and said elongated ribs and filter pad in contact therewith defining a multiplicity of channels Within said casing in a plane transverse to its axis for dividing the air into a plurality of streams and directing the streams through said channels toward the eccentrically disposed outlet.

References Cited in the file of this patent UNITED STATES PATENTS 1,021,254 Larkins Mar. 26, 1912 1,490,957 Birger Apr. 22, 1924 1,622,827 Hanson Mar. 29, 1927 2,151,842 Faber Mar. 28, 1939 2,155,669 Lofgren Apr. 25, 1939 2,719,596 Kent et al. Oct. 4, 1955 FOREIGN PATENTS 261,780 Great Britain Feb. 20, 1928 449,903 Great Britain June 30, 1936 638,702 Great Britain June 14, 1950 

